With a victory in Texas giving him a sweep of the South, plus the exclamation marks from winning outright in Massachusetts and Minnesota, Joe Biden is suddenly the front-runner again for the Democratic presidential nomination.
Senator Bernie Sanders leads in California, the biggest prize of Super Tuesday, which will keep the delegate count tight and probably ensures that the Democratic Party's nominating contest drags on for a few more months.
Sanders carried his home state of Vermont, as well as Colorado and Utah. But he crashed into a brick wall down South, just as he did four years ago against Hillary Clinton, despite his efforts to court African Americans.
Biden won Virginia, North Carolina, Tennessee, Arkansas, Alabama and Oklahoma by double digits. Maine, which the Sanders camp expected to carry, has been projected for Biden by AP. Sanders won Maine decisively in 2016.
"We increased turnout," Biden told supporters in Los Angeles. "The turnout turned out for us!"
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Turnout grew not because of Biden's ground game, which was essentially nonexistent in the 14 states and one US territory that voted yesterday. In fact, he won big in several places where he spent little time and made no real investment in a field programme.
After spending more than half a billion dollars of his personal fortune, former New York mayor Mike Bloomberg's only win came in American Samoa, where Representative Tulsi Gabbard also got a delegate. Bloomberg exited the race today, shifting his support to Biden.
Turnout also did not appear to grow because of a surge in young voters that Sanders keeps promising will materialise any time now. Exit polls show that about 1 in 8 voters in Super Tuesday states were 18- to 29-year-olds, compared to 3 in 10 who were 65 or older. Sanders struggles with these older voters.
Instead, turnout appears to have spiked from 2016 to 2020 in key general election battlegrounds because antipathy towards US President Donald Trump continues to galvanise suburban moderates to get engaged in Democratic politics.
A Washington Post statistical model suggests Biden won nearly 60 per cent of voters who sat out the 2016 primary but cast ballots. The turnout analysis, conducted by in-house data scientist Lenny Bronner, also shows that Biden possibly received nearly 90 per cent of Clinton's 2016 voters.
Biden romped in the suburbs, excelling with the constituencies that fuelled the Democratic takeover of the House in 2018.
In addition to his stalwart base of African American voters, the foundation of his wins across the South, Biden fared well with white voters in suburbs from Richmond, Virginia, and Raleigh, North Carolina, to Houston and Hampton Roads, Virginia, as well as Nashville, Tennessee, and Minneapolis.
Exit polls show that many decided to back the former vice-president in the days after his South Carolina landslide.
These voters think that he's the most electable choice to take back the White House and that beating Trump is more important to them than agreeing with a candidate on the issues.
It also helped Biden that the field winnowed, and he received endorsements from former South Bend, Indiana, mayor Pete Buttigieg and Senator Amy Klobuchar.
Biden credited his win in Minnesota, where Sanders invested heavily and held a massive rally on Tuesday, to Klobuchar. Exit polls there showed 6 in 10 voters decided whom to vote for in the past few days. Biden won about half that group.
1) Consider Virginia as a window into why turnout grew.
In 2016, 785,000 people participated in the Democratic primary. Yesterday, about 1.3 million people did. This broke the turnout record set in the 2008 primary that pitted Clinton against then-Senator Barack Obama.
About a quarter of Virginia primary voters were African American, and roughly 6 in 10 chose Biden, according to the exit polls. But Biden also won support from 6 in 10 white voters older than 45. While Sanders won 3 to 1 among younger voters, Biden still won the primary in Virginia by 30 points.
2) Biden won from coast to coast among those who identify as "somewhat liberal."
He dominated among conservative and moderate primary voters across most of the 14 states that voted, with the exceptions of Colorado and Vermont.
But he also fared very well among the large share of voters who self-identify as "somewhat liberal."
Biden won that group by a roughly 2-to-1 margin over Sanders in Alabama, Virginia and North Carolina. Those latter two states will be close contests in November.
3) Sanders' coalition is built around liberals and Latinos.
One reason he's widely expected to win California, although the race has not been called with 81 per cent of precincts reporting, is that two-thirds of voters described themselves as liberal in the exit polling, and this group voted more than 2 to 1 for Sanders.
Hispanic voters also showed a strong preference for Sanders in the states where they made up the largest shares of the Democratic electorate. About 3 in 10 voters in Texas identified themselves as Hispanic, and just under half of them voted for Sanders. Biden got about 1 in 4 Hispanic votes in the Lone Star State.
The share of Hispanic voters was slightly smaller in California, but Sanders won the group by a larger margin, capturing a majority. Biden got about 1 in 5 Latinos in the Golden State, giving Sanders a margin of about 30 percentage points, according to the exits.
4) Biden makes gains with white voters.
Elsewhere, though, Biden made inroads with non-college-educated whites who backed Sanders four years ago.
Exit polls suggested Biden had a greater than 2-to-1 lead among white voters in Alabama, and nearly as wide an edge in Virginia. Biden had a smaller but still visible lead among white voters in Minnesota and Oklahoma and a smaller edge in Tennessee, North Carolina and Massachusetts.
In Maine and Texas, Biden and Sanders were neck and neck among white voters. And Sanders led among white voters in Vermont, Colorado and California.
5) Decision time for Warren
Senator Elizabeth Warren's third-place finish in Massachusetts, a state she's represented in the Senate for eight years, makes continuing her campaign increasingly difficult to rationalise.
The Democrat also finished fourth in her native Oklahoma, with 13.4 per cent, under the 15 per cent threshold required to win any delegates, though not all the precincts have reported.
Speaking yesterday in Detroit as polls remained open in several states, Warren pledged to forge ahead and seemed to plead with late deciders not to keep breaking for Biden.
"What I see happening is a lot of folks trying to turn voting into some complicated strategy," she said, acting almost as if Super Tuesday hadn't happened. "They are playing games about prediction and strategy. Prediction has been a terrible business."